Re: [xsl] user-defined XSLT functions and stylesheet variables?

["Christophe Marchand cmarchand@xxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

All the responses given by Eliot and Liam respect Clean Code[1] best 
practises. Many principles must be respected if you expect your code may 
evolve :

  * DRY : Don't Repeat Yourself ; sometime in opposition with Single
    Responsability principle
  * YAGNI : You Ain't Gonna Need It
  * SOLID, with only some of them applicable to XSLT :
      o S : Single Responsability Principle: There must have no more
        than One reason to modifiy this piece of code
      o O : Open Close Principle: Open to Extension, Closed to Modification

All of these principles try to avoid use of global variables, even if 
it's not clearly written in the details of pirinciples. As Mike says, 
Evil is in the detail, but Evil is also in global variables.

HTH,
Christophe

[1] : clean Code, Bob Martin, Pearson Addison-Wesley, 2009

Le 18/06/2021 C  20:28, Eliot Kimber ekimber@xxxxxxxxxxxx a C)critB :
>
> If I was given a style sheet with a function that used a global 
> variable I would immediately rewrite the function to take that 
> variable as a parameter.
>
> Cheers,
>
> E.
>
> --
>
> Eliot Kimber
>
> http://contrext.com
>
> *From: *"Liam R. E. Quin liam@xxxxxxxxxxxxxxxx" 
> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
> *Reply-To: *<xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
> *Date: *Friday, June 18, 2021 at 12:56 PM
> *To: *<xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
> *Subject: *Re: [xsl] user-defined XSLT functions and stylesheet variables?
>
> On Fri, 2021-06-18 at 17:42 +0000, David Birnbaum djbpitt@xxxxxxxxx 
> <mailto:djbpitt@xxxxxxxxx>
>
> wrote:
>
>     Dear XSLT-list,
>
>     Is there agreement about Best Practice with respect to using
>
>     stylesheet
>
>     (global) variables inside user-defined functions?
>
> Tommie once gave a talk about best practice considered hamrful... :)
>
> You've identified some of the issues, but for me the most important
>
> ones are this:
>
> (1) locality of reference: can i understand thefunction without having
>
> to look elsewhere?
>
> (2) maintainability: how easy will it be to fix problems in this
>
> function in the future, or for someone else to change it, perhaps to
>
> workslightly differently on edge cases. Assume they are in a hurry.
>
> (3) can i take the function and reuse it in another stylesheet later?
>
> Overall the use of global variables is likely to be an impediment to
>
> each of these.
>
> Liam
>
> -- 
>
> Liam Quin, https://www.delightfulcomputing.com/ 
> <https://www.delightfulcomputing.com/>
>
> Available for XML/Document/Information Architecture/XSLT/
>
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>
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